1. Field of the Invention
The present invention relates to a phosphorous-containing catalyst composition and a hydroformylation process using the same, and more particularly, to a phosphorous-containing catalyst composition in which a combination of a monodentate phosphorous compound and a bidentate phosphorous compound is used as a ligand to a transition metal catalyst and a process of hydroformylation of olefin compounds comprising reacting the olefin compound with a gas mixture of hydrogen and carbon monoxide while being stirred at elevated pressures and temperatures in the presence of the above catalyst composition to produce aldehyde.
2. Description of the Related Art
The hydroformylation reaction, also known as the oxo reaction, includes reacting an olefin with a synthesis gas (CO/H2) in the presence of a metal catalyst and a ligand to produce a linear (normal) aldehyde and branched (iso) aldehyde which has one more carbon atom than the olefin. The oxo reaction was discovered by Otto Roelen in 1938. In 2001, about 8,400,000 tons of various aldehydes (including its alcohol derivatives) were produced through the oxo reaction worldwide (SRI Report, November 2002, 682. 700A). The various aldehydes synthesized according to the oxo reaction are converted to acids and alcohols through oxidation and reduction reactions. The aldehydes may be subjected to an aldol condensation reaction and then converted to acids and alcohols having a long alkyl chain through oxidation and reduction reactions. The obtained acids and alcohols are used as solvents, additives, raw materials for various plasticizers, and etc.
Cobalt (Co) or rhodium (Rh)-based catalysts are mostly used in the oxo reaction. Depending on the types of ligands and the operating conditions, different N/I (ratio of linear (normal) isomer to branched (iso) isomer) selectivity of aldehyde is obtained. At least 70% of all oxo plants have adopted a low pressure oxo process with a rhodium-based catalyst.
In addition to cobalt (Co) and rhodium (Rh), iridium (Ir), ruthenium (Ru), osmium (Os), planitum (Pt), palladium (Pd), iron (Fe), and nickel (Ni) can be used as a central metal in the catalyst for the oxo reaction. Catalytic activities of these metal complexes can be ordered as follows: Rh>>Co>Ir, Ru>Os>Pt>Pd>Fe>Ni. Therefore, most research and development have been focused on rhodium and cobalt. Examples of ligands in the catalyst may include phosphine (PR3, R═C6H5, n-C4H9), phosphine oxide (O═P(C6H5)3), phosphite, amine, amide, and isonitrile. There rarely exist ligands that are more advantageous in view of catalytic activity, stability, and cost than triphenylphosphine (TPP). Thus, in most oxo reactions, Rh metal is used as a catalyst and TPP and its derivatives are used as ligand. In addition, to increase the stability of a catalytic system, TPP ligand is used in an amount of at least 100 equivalent of the catalyst.
Eastman Kodak Company and Union Carbide Company (merged into Dow) developed a bidentate phosphine ligand having high catalytic activity and high N/I selectivity, respectively (see, U.S. Pat. Nos. 4,694,109 and 4,668,651).
Moloy and coworkers developed N-pyrrolyl phosphine which shows high activity and selectivity (JACS 1995, 117, 7696).
U.S. Pat. No. 5,710,344 describes a process for the preparation of linear aldehydes by hydroformylation using a bidentate ligand which contains at least one P—C or P—N bond.
As the application of iso aldehyde is developed, there is an increasing need for iso aldehyde. However, since the conventional catalyst compositions have high selectivity to normal aldehyde, increase of production of iso aldehyde is limited. Thus, there is a need for a process of producing a normal aldehyde and an iso aldehyde in a desired ratio by controlling N/I selectivity while maintaining a sufficient catalytic activity.